The owner of a Tribeca jewelry store slapped ADT Security Services with a “gross negligence” suit today over claims that a faulty burglar alarm let brazen thieves make off with more than $2 million worth of gems last year.

Amit Sharma further charges that ADT committed fraud when “someone” there forged his signature on an agreement limiting the company’s liability for the break-in at his store to a measly $1,000.

“In fact, [Sharma] never signed the agreement…a conclusion supported by an independent handwriting analysis,” says the suit.

The Manhattan federal court filing seeks at least $2.4 million for the loss of the valuable inventory, and at least $10 million more for the “willful, malicious and reprehensible” forgery of Sharma’s signature.

According to court papers, Sharma closed up his store at 246 West Broadway and armed the ADT system shortly after 8 p.m. on Dec. 4, 2010.

But when he arrived for work the next morning, Sharma found the lock to the building glued shut — leading to the discovery that his shop had been burglarized.

“Specifically, a hole had been cut in the ceiling to the office, from which a ladder remained hanging down,” court papers say.

In addition, the door to the store’s safe “had been completely sawed off” — which a cop at the scene said “must have taken at least 45 minutes” — and “more than 150 different pieces of jewelry and loose stones” were gone.

Video from a surveillance camera inside the store revealed that one of the burglars had shined a flashlight onto an ADT sensor, “presumably to test if the alarm system was working.”

“According to the police, it was believed that the burglars had possession of a police scanner and were likely listening to see if the police had been notified by ADT of the break-in,” the suit says.

But even though the alarm had been triggered, “no signal was transmitted to ADT’s central monitoring system, and, accordingly, no call was made by ADT to (Sharma) or the police.”

“Given the substantial time that passed between the burglars’ initial descent through the ceiling of Nirvana’s back office and their completion of the removal of the door to Nirvana’s safe — more than an hour even by conservative estimates — it seems obvious that had ADT’s alarm system properly functioned, this burglary would have been prevented,” court papers charge.